TypeError when a single language is active together with translation and detection

If you only have 1 language enabled together with the translation modules and then you activate the URL interface text language detection (Detection and selection), you get the following error:

TypeError: Argument 1 passed to Drupal\language\LanguageNegotiationMethodBase::setCurrentUser() must implement interface Drupal\Core\Session\AccountInterface

This seems to be because the LanguageSwitchLinks are disabled in this case, only on some admin pages.

I suggest to disable the alternate hreflang feature on admin pages to avoid this issue. Admin pages do not need to have a hreflang anyhow.